bims-glucam 2021-01-17 papers

bims-glucam

Biomed News

on Glutamine cancer metabolism

Issue of 2021‒01‒17
eighteen papers selected by
Sreeparna Banerjee
Middle East Technical University

Bone metastatic breast cancer cells display downregulation of PKC-ζ with enhanced glutamine metabolism.
Metabolic Constants and Plasticity of Cancer Cells in a Limiting Glucose and Glutamine Microenvironment-A Pyruvate Perspective.
Global Changes to HepG2 Cell Metabolism in Response to Galactose Treatment.
L-type amino acid transporter 1 is associated with chemoresistance in breast cancer via the promotion of amino acid metabolism.
Discovery of a Redox Thiol Switch: Implications for Cellular Energy Metabolism.
Resveratrol's Anti-Cancer Effects through the Modulation of Tumor Glucose Metabolism.
Current Understanding on the Metabolism of Neutrophils.
Glutaminase inhibition with telaglenastat (CB-839) improves treatment response in combination with ionizing radiation in head and neck squamous cell carcinoma models.
Non-coding RNAs rewire cancer metabolism networks.
Targeting hypoxic tumor microenvironment in pancreatic cancer.
Reaction between Graphene Oxide and Intracellular Glutathione Affects Cell Viability and Proliferation.
Oncometabolite L-2-hydroxyglurate directly induces vasculogenic mimicry through PHLDB2 in renal cell carcinoma.
The harsh microenvironment in early breast cancer selects for a Warburg phenotype.
Rhythmic glucose metabolism regulates the redox circadian clockwork in human red blood cells.
Investigating the Thioredoxin and Glutathione Systems' Response in Lymphoma Cells after Treatment with [Au(d2pype)2]CL.
Nrf2 regulates cell motility through RhoA-ROCK1 signalling in non-small-cell lung cancer cells.
Senolysis by glutaminolysis inhibition ameliorates various age-associated disorders.
Crystal structure of glutamate dehydrogenase 2, a positively selected novel human enzyme involved in brain biology and cancer pathophysiology.

Gene. 2021 Jan 11. pii: S0378-1119(21)00013-5. [Epub ahead of print] 145419

Bone metastatic breast cancer cells display downregulation of PKC-ζ with enhanced glutamine metabolism.

Manish Tandon, Ahmad H Othman, Marcus Winogradzki, Jitesh Pratap.

BACKGROUND: Breast cancer is the most commonly diagnosed cancer among women and its metastases results in poor survival rates in patients. The ability to alter metabolism is a key attribute cancer cells use to survive within different metastatic microenvironments and cause organ failure. We hypothesized that evaluation of metabolic alterations within tumor cells could provide a better understanding of cancer metastasis. Therefore, to investigate underlying metabolic alterations during metastases, we utilized human MDA-MB-231 and mouse 4T1 models that closely mimic human breast cancer metastasis.METHODS: The glycolysis and glutamine pathway-related changes were examined in bone metastatic cells by XF-24 extracellular flux analyzer and western blotting. The expression levels of genes related to metabolism were examined by PCR arrays.
RESULTS: The MDA-MB-231 cells isolated after bone metastases showed reduced glucose uptake and glycolysis compared to parental cells, suggesting that these cells could alter metabolic requirements for survival. To understand these metabolic changes, we investigated glutamine, a common and naturally occurring non-essential amino acid. Interestingly, in reduced glucose conditions both cell lines showed dependence on glutamine for cell survival, and with glutamine withdrawal significantly increasing apoptotic cell death. Glutamine was also critical for normal cell proliferation even in the presence of high glucose concentrations. To further understand this metabolic switch in metastatic cells, we examined the genes related to metabolism and identified a more than seven-fold downregulation of protein kinase C zeta (PKC-ζ) expression levels in bone-derived MDA-MB-231 cells compared to the parental population. The PKC-ζ levels were also significantly reduced in metastatic 4T1 cells compared to non-metastatic MT1A2 cells. Since PKC-ζ deficiency promotes glutamine utilization via the serine biosynthesis pathway, we examined glutamine metabolism. The ectopic expression of PKC-ζ inhibited glutamine conversion to glutamate, while mutant PKC-ζ reversed this effect. Furthermore, the gene expression levels of enzymes involved in serine biosynthesis, phosphoserine phosphatase (PSPH), phosphoserine aminotransferase (PSAT1), and phosphoglycerate dehydrogenase (PHGDH) showed upregulation following glucose deprivation with PKC-ζ deficiency. The PHGDH upregulation was inhibited by ectopically expressing wild type but not mutated PKC-ζ in glucose-deprived conditions.
CONCLUSIONS: Our results support the upregulation of serine biosynthesis pathway genes and downregulation of PKC-ζ as potential metabolic alterations for bone metastatic breast cancer cells.

DOI: https://doi.org/10.1016/j.gene.2021.145419
Front Oncol. 2020 ;10 596197

Metabolic Constants and Plasticity of Cancer Cells in a Limiting Glucose and Glutamine Microenvironment-A Pyruvate Perspective.

Angela M Otto.

  The metabolism of cancer cells is an issue of dealing with fluctuating and limiting levels of nutrients in a precarious microenvironment to ensure their vitality and propagation. Glucose and glutamine are central metabolites for catabolic and anabolic metabolism, which is in the limelight of numerous diagnostic methods and therapeutic targeting. Understanding tumor metabolism in conditions of nutrient depletion is important for such applications and for interpreting the readouts. To exemplify the metabolic network of tumor cells in a model system, the fate 13C6-glucose was tracked in a breast cancer cell line growing in variable low glucose/low glutamine conditions. 13C-glucose-derived metabolites allowed to deduce the engagement of metabolic pathways, namely glycolysis, the TCA-cycle including glutamine and pyruvate anaplerosis, amino acid synthesis (serine, glycine, aspartate, glutamate), gluconeogenesis, and pyruvate replenishment. While the metabolic program did not change, limiting glucose and glutamine supply reduced cellular metabolite levels and enhanced pyruvate recycling as well as pyruvate carboxylation for entry into the TCA-cycle. Otherwise, the same metabolic pathways, including gluconeogenesis, were similarly engaged with physiologically saturating as with limiting glucose and glutamine. Therefore, the metabolic plasticity in precarious nutritional microenvironment does not require metabolic reprogramming, but is based on dynamic changes in metabolite quantity, reaction rates, and directions of the existing metabolic network.

Keywords:  13C-glucose tracing; TCA-cycle; anaplerosis; glutamine; glycolysis; metabolic network; nutrient deprivation; pyruvate replenishment

DOI:  https://doi.org/10.3389/fonc.2020.596197
Am J Physiol Cell Physiol. 2021 Jan 13.

Global Changes to HepG2 Cell Metabolism in Response to Galactose Treatment.

Robert A Skolik, Jason Solocinski, Mary E Konkle, Nilay Chakraborty, Michael A Menze.

  Tumor cell proliferation requires sufficient metabolic flux through the pentose phosphate pathway to meet the demand for biosynthetic precursors and to increase protection against oxidative stress which in turn requires an upregulation of substrate flow through glycolysis. This metabolic poise is often coupled with a shift in ATP production from mitochondrial OXPHOS to substrate-level phosphorylation. Despite major advances that were facilitated by using tumor-derived cell lines in research areas spanning from membrane to cytoskeletal biology, this distorted metabolic profile limits their impact as a model in physiology and toxicology. Substitution of glucose with galactose in the cell culture medium has been demonstrated to shift ATP production from substrate-level phosphorylation to mitochondrial OXPHOS. This increase in oxygen utilization is coupled to a global metabolic reorganization with potential impacts on macromolecule biosynthesis and cellular redox homeostasis, but a comprehensive analysis on the effects of sugar substitution in tumor-derived cells is still missing. To address this gap in knowledge we performed transcriptomic and metabolomic analyses on human hepatocellular carcinoma (HepG2) cells adapted to either glucose or galactose as the aldohexose source. We observed a shift towards oxidative metabolism in all primary metabolic pathways at both transcriptomic and metabolomic levels. We also observed a decrease in nicotinamide dinucleotide (NAD(P)) levels and subcellular NAD+-to-NADH ratios in cells cultured with galactose compared to glucose control cells. Our results suggest that galactose reduces both glycolytic and biosynthetic flux and restores a metabolic poise in HepG2 cells that closely reflects the metabolic state observed in primary hepatocytes.

Keywords:  Cancer; Galactose; Mitochondria; NAD; Redox state

DOI:  https://doi.org/10.1152/ajpcell.00460.2020
Sci Rep. 2021 Jan 12. 11(1): 589

L-type amino acid transporter 1 is associated with chemoresistance in breast cancer via the promotion of amino acid metabolism.

Miku Sato, Narumi Harada-Shoji, Takafumi Toyohara, Tomoyoshi Soga, Masatoshi Itoh, Minoru Miyashita, Hiroshi Tada, Masakazu Amari, Naohiko Anzai, Shozo Furumoto, Takaaki Abe, Takashi Suzuki, Takanori Ishida, Hironobu Sasano.

18F-FDG PET/CT has been used as an indicator of chemotherapy effects, but cancer cells can remain even when no FDG uptake is detected, indicating the importance of exploring other metabolomic pathways. Therefore, we explored the amino acid metabolism, including L-type amino acid transporter-1 (LAT1), in breast cancer tissues and clarified the role of LAT1 in therapeutic resistance and clinical outcomes of patients. We evaluated LAT1 expression before and after neoadjuvant chemotherapy and examined the correlation of glucose uptake using FDG-PET with the pathological response of patients. It revealed that LAT1 levels correlated with proliferation after chemotherapy, and amino acid and glucose metabolism were closely correlated. In addition, LAT1 was considered to be involved in treatment resistance and sensitivity only in luminal type breast cancer. Results of in vitro analyses revealed that LAT1 promoted amino acid uptake, which contributed to energy production by supplying amino acids to the TCA cycle. However, in MCF-7 cells treated with chemotherapeutic agents, oncometabolites and branched-chain amino acids also played a pivotal role in energy production and drug resistance, despite decreased glucose metabolism. In conclusion, LAT1 was involved in drug resistance and could be a novel therapeutic target against chemotherapy resistance in luminal type breast cancer.

DOI: https://doi.org/10.1038/s41598-020-80668-5
Mol Cell Proteomics. 2020 May;pii: S1535-9476(20)35008-8. [Epub ahead of print]19(5): 852-870

Discovery of a Redox Thiol Switch: Implications for Cellular Energy Metabolism.

Xing-Huang Gao, Ling Li, Marc Parisien, Jing Wu, Ilya Bederman, Zhaofeng Gao, Dawid Krokowski, Steven M Chirieleison, Derek Abbott, Benlian Wang, Peter Arvan, Mark Cameron, Mark Chance, Belinda Willard, Maria Hatzoglou.

  The redox-based modifications of cysteine residues in proteins regulate their function in many biological processes. The gas molecule H2S has been shown to persulfidate redox sensitive cysteine residues resulting in an H2S-modified proteome known as the sulfhydrome. Tandem Mass Tags (TMT) multiplexing strategies for large-scale proteomic analyses have become increasingly prevalent in detecting cysteine modifications. Here we developed a TMT-based proteomics approach for selectively trapping and tagging cysteine persulfides in the cellular proteomes. We revealed the natural protein sulfhydrome of two human cell lines, and identified insulin as a novel substrate in pancreatic beta cells. Moreover, we showed that under oxidative stress conditions, increased H2S can target enzymes involved in energy metabolism by switching specific cysteine modifications to persulfides. Specifically, we discovered a Redox Thiol Switch, from protein S-glutathioinylation to S-persulfidation (RTSGS). We propose that the RTSGS from S-glutathioinylation to S-persulfidation is a potential mechanism to fine tune cellular energy metabolism in response to different levels of oxidative stress.

Keywords:  H2S; Post-translational modifications; chemoproteomics; cysteine modifications; diabetes; energy metabolism; glutathionylation; persulfidation; protein sulfhydrome; quantification; tandem mass spectrometry; thiol redox chemistry

DOI:  https://doi.org/10.1074/mcp.RA119.001910
Cancers (Basel). 2021 Jan 07. pii: E188. [Epub ahead of print]13(2):

Resveratrol's Anti-Cancer Effects through the Modulation of Tumor Glucose Metabolism.

Aranka Brockmueller, Saba Sameri, Alena Liskova, Kevin Zhai, Elizabeth Varghese, Samson Mathews Samuel, Dietrich Büsselberg, Peter Kubatka, Mehdi Shakibaei.

  Tumor cells develop several metabolic reprogramming strategies, such as increased glucose uptake and utilization via aerobic glycolysis and fermentation of glucose to lactate; these lead to a low pH environment in which the cancer cells thrive and evade apoptosis. These characteristics of tumor cells are known as the Warburg effect. Adaptive metabolic alterations in cancer cells can be attributed to mutations in key metabolic enzymes and transcription factors. The features of the Warburg phenotype may serve as promising markers for the early detection and treatment of tumors. Besides, the glycolytic process of tumors is reversible and could represent a therapeutic target. So-called mono-target therapies are often unsafe and ineffective, and have a high prevalence of recurrence. Their success is hindered by the ability of tumor cells to simultaneously develop multiple chemoresistance pathways. Therefore, agents that modify several cellular targets, such as energy restriction to target tumor cells specifically, have therapeutic potential. Resveratrol, a natural active polyphenol found in grapes and red wine and used in many traditional medicines, is known for its ability to target multiple components of signaling pathways in tumors, leading to the suppression of cell proliferation, activation of apoptosis, and regression in tumor growth. Here, we describe current knowledge on the various mechanisms by which resveratrol modulates glucose metabolism, its potential as an imitator of caloric restriction, and its therapeutic capacity in tumors.

Keywords:  anti-tumor action; combinatorial therapy; resveratrol; tumor glucose metabolism; warburg phenomenon

DOI:  https://doi.org/10.3390/cancers13020188
Immune Netw. 2020 Dec;20(6): e46

Current Understanding on the Metabolism of Neutrophils.

Jae-Han Jeon, Chang-Won Hong, Eun Young Kim, Jae Man Lee.

  Neutrophils are innate immune cells that constitute the first line of defense against invading pathogens. Due to this characteristic, they are exposed to diverse immunological environments wherein sources for nutrients are often limited. Recent advances in the field of immunometabolism revealed that neutrophils utilize diverse metabolic pathways in response to immunological challenges. In particular, neutrophils adopt specific metabolic pathways for modulating their effector functions in contrast to other immune cells, which undergo metabolic reprogramming to ensure differentiation into distinct cell subtypes. Therefore, neutrophils utilize different metabolic pathways not only to fulfill their energy requirements, but also to support specialized effector functions, such as neutrophil extracellular trap formation, ROS generation, chemotaxis, and degranulation. In this review, we discuss the basic metabolic pathways used by neutrophils and how these metabolic alterations play a critical role in their effector functions.

Keywords:  Immunology; Immunometabolism; Innate immunity; Metabolism; Neutrophils

DOI:  https://doi.org/10.4110/in.2020.20.e46
Cancer Lett. 2021 Jan 12. pii: S0304-3835(21)00001-X. [Epub ahead of print]

Glutaminase inhibition with telaglenastat (CB-839) improves treatment response in combination with ionizing radiation in head and neck squamous cell carcinoma models.

Christina A Wicker, Brian G Hunt, Sunil Krishnan, Kathryn Aziz, Shobha Parajuli, Sarah Palackdharry, William R Elaban, Trisha M Wise-Draper, Gordon B Mills, Susan E Waltz, Vinita Takiar.

  The efficacy of ionizing radiation (IR) for head and neck cancer squamous cell carcinoma (HNSCC) is limited by poorly understood mechanisms of adaptive radioresistance. Elevated glutaminase gene expression is linked to significantly reduced survival (p < 0.03). The glutaminase inhibitor, telaglenastat (CB-839), has been tested in Phase I/II cancer trials and is well tolerated by patients. This study investigated if telaglenastat enhances the cellular response to IR in HNSCC models. Using three human HNSCC cell lines and two xenograft mouse models, we examined telaglenastat's effects on radiation sensitivity. IR and telaglenastat combinatorial treatment reduced cell survival (p ≤ 0.05), spheroid size (p ≤ 0.0001) and tumor growth in CAL-27 xenograft bearing mice relative to vehicle (p ≤ 0.01), telaglenastat (p ≤ 0.05) or IR (p ≤ 0.01) monotherapy. Telaglenastat significantly reduced the Oxygen Consumption Rate/Extracellular Acidification Rate ratio in CAL-27 and HN5 cells in the presence of glucose and glutamine (p ≤ 0.0001). Telaglenastat increased oxidative stress and DNA damage in irradiated CAL-27 cells. These data suggest that combination treatment with IR and telaglenastat leads to an enhanced anti-tumor response. This pre-clinical data, combined with the established safety of telaglenastat justifies further investigation for the combination in HNSCC patients.

Keywords:  Combinatorial therapy; Preclinical models; Radioresistance; Radiosensitivity; Small molecule inhibitor

DOI:  https://doi.org/10.1016/j.canlet.2020.12.038
Semin Cancer Biol. 2021 Jan 06. pii: S1044-579X(20)30280-7. [Epub ahead of print]

Non-coding RNAs rewire cancer metabolism networks.

Xiaorong Lin, Zhiyong Wu, Hai Hu, Man-Li Luo, Erwei Song.

  Non-coding RNAs (ncRNAs) are functional RNAs with limited or no protein-coding ability. These interact with their target molecules and participate in the precise regulation of disease development. Metabolic reprogramming is a hallmark in cancer, and is considered essential in meeting increased macromolecular biosynthesis and energy generation of tumors. Recent studies have revealed the involvement of ncRNAs in several metabolic regulations of cancer through direct modulation of metabolic enzyme activities or participation of metabolism-related signaling pathways. Elucidation of how ncRNAs regulate metabolic reprogramming of cancers has opened up a novel intention to understand the mechanism of metabolic rewiring and also the opportunities of utilizing ncRNA-based therapeutics for targeting the metabolism in cancer treatment.

Keywords:  Cancer; Metabolism networks; Tumor microenvironment; ncRNA-based therapeutics; ncRNAs

DOI:  https://doi.org/10.1016/j.semcancer.2020.12.019
J Hematol Oncol. 2021 Jan 13. 14(1): 14

Targeting hypoxic tumor microenvironment in pancreatic cancer.

Jinxin Tao, Gang Yang, Wenchuan Zhou, Jiangdong Qiu, Guangyu Chen, Wenhao Luo, Fangyu Zhao, Lei You, Lianfang Zheng, Taiping Zhang, Yupei Zhao.

  Attributable to its late diagnosis, early metastasis, and poor prognosis, pancreatic cancer remains one of the most lethal diseases worldwide. Unlike other solid tumors, pancreatic cancer harbors ample stromal cells and abundant extracellular matrix but lacks vascularization, resulting in persistent and severe hypoxia within the tumor. Hypoxic microenvironment has extensive effects on biological behaviors or malignant phenotypes of pancreatic cancer, including metabolic reprogramming, cancer stemness, invasion and metastasis, and pathological angiogenesis, which synergistically contribute to development and therapeutic resistance of pancreatic cancer. Through various mechanisms including but not confined to maintenance of redox homeostasis, activation of autophagy, epigenetic regulation, and those induced by hypoxia-inducible factors, intratumoral hypoxia drives the above biological processes in pancreatic cancer. Recognizing the pivotal roles of hypoxia in pancreatic cancer progression and therapies, hypoxia-based antitumoral strategies have been continuously developed over the recent years, some of which have been applied in clinical trials to evaluate their efficacy and safety in combinatory therapies for patients with pancreatic cancer. In this review, we discuss the molecular mechanisms underlying hypoxia-induced aggressive and therapeutically resistant phenotypes in both pancreatic cancerous and stromal cells. Additionally, we focus more on innovative therapies targeting the tumor hypoxic microenvironment itself, which hold great potential to overcome the resistance to chemotherapy and radiotherapy and to enhance antitumor efficacy and reduce toxicity to normal tissues.

Keywords:  Angiogenesis; Autophagy; EMT and metastasis; Hypoxia; Innovative therapies; Metabolic reprogramming; Pancreatic cancer; Redox homeostasis; Stemness; Therapeutic resistance

DOI:  https://doi.org/10.1186/s13045-020-01030-w
ACS Appl Mater Interfaces. 2021 Jan 11.

Reaction between Graphene Oxide and Intracellular Glutathione Affects Cell Viability and Proliferation.

Baojin Ma, Shi Guo, Yuta Nishina, Alberto Bianco.

  Graphene oxide (GO) is currently developed for biomedical applications as a promising nanoplatform for drug delivery, phototherapy, and biosensing. As a consequence, its safety and cytotoxicity issues have attracted extensive attention. It has been demonstrated that GO causes an increase of intracellular oxidative stress, likely leading to its cytotoxicity and inhibition of cell proliferation. Being one of the main reductive intracellular substances, glutathione (GSH) is vital in the regulation of the oxidative stress level to maintain normal cellular functions. In this study, we found that GSH could be oxidized to GSSG by GO, leading to the formation of reduced GO (rGO). GSH depletion affects the intracellular reductive/oxidative balance, provoking the increase of the reactive oxygen species level, sequentially inhibiting cell viability and proliferation. Therefore, the reaction between GO and GSH provides a new perspective to explain the origin of GO cytotoxicity.

Keywords:  cancer cells; carbon nanomaterial; oxidation; reactive oxygen species; reduction

DOI:  https://doi.org/10.1021/acsami.0c17523
Int J Cancer. 2020 Dec 15.

Oncometabolite L-2-hydroxyglurate directly induces vasculogenic mimicry through PHLDB2 in renal cell carcinoma.

Huan Wang, Liya Wang, Qiming Zheng, Zeyi Lu, Yuanlei Chen, Danyang Shen, Dingwei Xue, Minxiao Jiang, Lifeng Ding, Jie Zhang, Haiyang Wu, Liqun Xia, Jun Qian, Gonghui Li, Jieyang Lu.

  Metabolism reprograming is a hallmark of cancer and plays an important role in tumor progression. The aberrant metabolism in renal cell carcinoma (RCC) leads to accumulation of the oncometabolite L-2-hydroxyglurate (L-2HG). L-2HG has been reported to inhibit the activity of some α-ketoglutarate-dependent dioxygenases such as TET enzymes, which mediate epigenetic alteration, including DNA and histone demethylation. However, the detailed functions of L-2HG in renal cell carcinoma have not been investigated thoroughly. In our study, we found that L-2HG was significantly elevated in tumor tissues compared to adjacent tissues. Furthermore, we demonstrated that L-2HG promoted vasculogenic mimicry (VM) in renal cancer cell lines through reducing the expression of PHLDB2. A mechanism study revealed that activation of the ERK1/2 pathway was involved in L-2HG-induced VM formation. In conclusion, these findings highlighted the pathogenic link between L-2HG and VM and suggested a novel therapeutic target for RCC.

Keywords:  2-hydroxyglutarate; epigenetics; oncometabolite; renal cell carcinoma; vasculogenic mimicry

DOI:  https://doi.org/10.1002/ijc.33435
Proc Natl Acad Sci U S A. 2021 Jan 19. pii: e2011342118. [Epub ahead of print]118(3):

The harsh microenvironment in early breast cancer selects for a Warburg phenotype.

Mehdi Damaghi, Jeffrey West, Mark Robertson-Tessi, Liping Xu, Meghan C Ferrall-Fairbanks, Paul A Stewart, Erez Persi, Brooke L Fridley, Philipp M Altrock, Robert A Gatenby, Peter A Sims, Alexander R A Anderson, Robert J Gillies.

  The harsh microenvironment of ductal carcinoma in situ (DCIS) exerts strong evolutionary selection pressures on cancer cells. We hypothesize that the poor metabolic conditions near the ductal center foment the emergence of a Warburg Effect (WE) phenotype, wherein cells rapidly ferment glucose to lactic acid, even in normoxia. To test this hypothesis, we subjected low-glycolytic breast cancer cells to different microenvironmental selection pressures using combinations of hypoxia, acidosis, low glucose, and starvation for many months and isolated single clones for metabolic and transcriptomic profiling. The two harshest conditions selected for constitutively expressed WE phenotypes. RNA sequencing analysis of WE clones identified the transcription factor KLF4 as potential inducer of the WE phenotype. In stained DCIS samples, KLF4 expression was enriched in the area with the harshest microenvironmental conditions. We simulated in vivo DCIS phenotypic evolution using a mathematical model calibrated from the in vitro results. The WE phenotype emerged in the poor metabolic conditions near the necrotic core. We propose that harsh microenvironments within DCIS select for a WE phenotype through constitutive transcriptional reprogramming, thus conferring a survival advantage and facilitating further growth and invasion.

Keywords:  DCIS; Warburg Effect; adaptation; clonal selection; tumor evolution

DOI:  https://doi.org/10.1073/pnas.2011342118
Nat Commun. 2021 Jan 15. 12(1): 377

Rhythmic glucose metabolism regulates the redox circadian clockwork in human red blood cells.

Ratnasekhar Ch, Guillaume Rey, Sandipan Ray, Pawan K Jha, Paul C Driscoll, Mariana Silva Dos Santos, Dania M Malik, Radoslaw Lach, Aalim M Weljie, James I MacRae, Utham K Valekunja, Akhilesh B Reddy.

Circadian clocks coordinate mammalian behavior and physiology enabling organisms to anticipate 24-hour cycles. Transcription-translation feedback loops are thought to drive these clocks in most of mammalian cells. However, red blood cells (RBCs), which do not contain a nucleus, and cannot perform transcription or translation, nonetheless exhibit circadian redox rhythms. Here we show human RBCs display circadian regulation of glucose metabolism, which is required to sustain daily redox oscillations. We found daily rhythms of metabolite levels and flux through glycolysis and the pentose phosphate pathway (PPP). We show that inhibition of critical enzymes in either pathway abolished 24-hour rhythms in metabolic flux and redox oscillations, and determined that metabolic oscillations are necessary for redox rhythmicity. Furthermore, metabolic flux rhythms also occur in nucleated cells, and persist when the core transcriptional circadian clockwork is absent in Bmal1 knockouts. Thus, we propose that rhythmic glucose metabolism is an integral process in circadian rhythms.

DOI: https://doi.org/10.1038/s41467-020-20479-4
Antioxidants (Basel). 2021 Jan 13. pii: E104. [Epub ahead of print]10(1):

Investigating the Thioredoxin and Glutathione Systems' Response in Lymphoma Cells after Treatment with [Au(d2pype)2]CL.

Sicong Wang, Yaoying Lu, Kyra Woods, Giovanna Di Trapani, Kathryn F Tonissen.

  Lymphoma is a blood cancer comprising various subtypes. Although effective therapies are available, some patients fail to respond to treatment and can suffer from side effects. Antioxidant systems, especially the thioredoxin (Trx) and glutathione (GSH) systems, are known to enhance cancer cell survival, with thioredoxin reductase (TrxR) recently reported as a potential anticancer target. Since the GSH system can compensate for some Trx system functions, we investigated its response in three lymphoma cell lines after inhibiting TrxR activity with [Au(d2pype)2]Cl, a known TrxR inhibitor. [Au(d2pype)2]Cl increased intracellular reactive oxygen species (ROS) levels and induced caspase-3 activity leading to cell apoptosis through inhibiting both TrxR and glutathione peroxidase (Gpx) activity. Expression of the tumour suppresser gene TXNIP increased, while GPX1 and GPX4 expression, which are related to poor prognosis of lymphoma patients, decreased. Unlike SUDHL2 and SUDHL4 cells, which exhibited a decreased GSH/GSSG ratio after treatment, in KMH2 cells the ratio remained unchanged, while glutathione reductase and glutaredoxin expression increased. Since KMH2 cells were less sensitive to treatment with [Au(d2pype)2]Cl, the GSH system may play a role in protecting cells from apoptosis after TrxR inhibition. Overall, our study demonstrates that inhibition of TrxR represents a valid therapeutic approach for lymphoma.

Keywords:  ROS; apoptosis; glutathione; gold-based compounds; lymphoma; thioredoxin

DOI:  https://doi.org/10.3390/antiox10010104
Sci Rep. 2021 Jan 13. 11(1): 1247

Nrf2 regulates cell motility through RhoA-ROCK1 signalling in non-small-cell lung cancer cells.

Eunsun Ko, Dasom Kim, Dong Wha Min, Seung-Hae Kwon, Ji-Yun Lee.

Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a key transcriptional regulator of several antioxidant and anti-inflammatory enzymes. It binds to its endogenous inhibitor Kelch-like ECH-associated protein 1 (Keap1) in the cytoplasm under normal conditions. Various endogenous or environmental oxidative stresses can disrupt the Nrf2/Keap1 complex, allowing Nrf2 to translocate into the nucleus, where it induces the transcription of various cytoprotective enzymes by binding to antioxidant responsive elements. These enzymes have been reported to play a role in regulating tumour growth, angiogenesis, and chemoprevention. Invasion and migration are the most harmful aspects of cancer; they directly impacts the patients' survival. Although the roles of Keap1/Nrf2 and their downstream genes in various cancers have been widely documented, their role in regulating cell motility still remains unclear, particularly in cancer cells. We observed that Nrf2 suppression following treatment with brusatol in non-small-cell lung cancer (NSCLC) cells with either exogenously introduced Keap1 or siNrf2 resulted in the inhibition of cell migration and invasion, with shrinking cell morphology due to decreased focal adhesions via inhibition of the RhoA-ROCK1 pathway. Nrf2 overexpression showed opposite results. Thus, the Nrf2/Keap1 pathway may affect cell motility by dysregulating the RhoA-ROCK1 signalling pathway in NSCLC.

DOI: https://doi.org/10.1038/s41598-021-81021-0
Science. 2021 01 15. 371(6526): 265-270

Senolysis by glutaminolysis inhibition ameliorates various age-associated disorders.

Yoshikazu Johmura, Takehiro Yamanaka, Satotaka Omori, Teh-Wei Wang, Yuki Sugiura, Masaki Matsumoto, Narumi Suzuki, Soichiro Kumamoto, Kiyoshi Yamaguchi, Seira Hatakeyama, Tomoyo Takami, Rui Yamaguchi, Eigo Shimizu, Kazutaka Ikeda, Nobuyuki Okahashi, Ryuta Mikawa, Makoto Suematsu, Makoto Arita, Masataka Sugimoto, Keiichi I Nakayama, Yoichi Furukawa, Seiya Imoto, Makoto Nakanishi.

Removal of senescent cells (senolysis) has been proposed to be beneficial for improving age-associated pathologies, but the molecular pathways for such senolytic activity have not yet emerged. Here, we identified glutaminase 1 (GLS1) as an essential gene for the survival of human senescent cells. The intracellular pH in senescent cells was lowered by lysosomal membrane damage, and this lowered pH induced kidney-type glutaminase (KGA) expression. The resulting enhanced glutaminolysis induced ammonia production, which neutralized the lower pH and improved survival of the senescent cells. Inhibition of KGA-dependent glutaminolysis in aged mice eliminated senescent cells specifically and ameliorated age-associated organ dysfunction. Our results suggest that senescent cells rely on glutaminolysis, and its inhibition offers a promising strategy for inducing senolysis in vivo.

DOI: https://doi.org/10.1126/science.abb5916
J Neurochem. 2021 Jan 09.

Crystal structure of glutamate dehydrogenase 2, a positively selected novel human enzyme involved in brain biology and cancer pathophysiology.

Christina Dimovasili, Vasiliki E Fadouloglou, Aikaterini Kefala, Mary Providaki, Dina Kotsifaki, Konstantinos Kanavouras, Iosifina Sarrou, Andreas Plaitakis, Ioannis Zaganas, Michael Kokkinidis.

  INTRODUCTION: Mammalian glutamate dehydrogenase (hGDH1 in human cells) interconverts glutamate to α-ketoglutarate and ammonia while reducing NAD(P) to NAD(P)H. During primate evolution, humans and great apes have acquired hGDH2, an isoenzyme that underwent rapid evolutionary adaptation concomitantly with brain expansion, thereby acquiring unique catalytic and regulatory properties that permitted its function under conditions inhibitory to its ancestor hGDH1. Although the 3D-structures of GDHs, including hGDH1, have been determined, attempts to determine the hGDH2 structure were until recently unsuccessful.HYPOTHESIS/AIM: Comparison of the hGDH1/hGDH2 structures would enable a detailed understanding of their evolutionary differences. This work aimed at the determination of the hGDH2 crystal structure and the analysis of its functional implications.
METHODS: Recombinant hGDH2 was produced in the Spodoptera frugiperda ovarian cell line Sf21, using the Baculovirus expression system. Purification was achieved via a two-step chromatography procedure. hGDH2 was crystallized, X-ray diffraction data were collected using synchrotron radiation and the structure was determined by molecular replacement.
RESULTS: The hGDH2 structure is reported at a resolution of 2.9 Å. The enzyme adopts a novel semi-closed conformation, which is an intermediate between known open and closed GDH1 conformations, differing from both. The structure enabled us to dissect previously reported biochemical findings and to structurally interpret the effects of evolutionary amino acid substitutions, including Arg470His, on ADP affinity.
CONCLUSIONS: Our data provide insights into the structural basis of hGDH2 properties, the functional evolution of hGDH isoenzymes, and open new prospects for drug design, especially for cancer therapeutics.

Keywords:  Glutamate dehydrogenase; crystal structure; mitochondrial metabolism; molecular evolution; structure-function relationships

DOI:  https://doi.org/10.1111/jnc.15296